Why the Olympics Are Unlikely to Spread Zika

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Photo: Matthew Stockman

People traveling to Brazil for the Rio Olympics are unlikely to worsen the spread of the Zika virus for two reasons: the weather, and because the number of Olympics travelers is relatively small, the Centers for Disease Control and Prevention said today.

It’s currently winter in Brazil and while they’re not expecting snow or anything, average temperatures in the 70s are cool enough to reduce mosquito populations and activity. Mosquitoes are the main route of transmission, although the virus can also be contracted through unprotected sex.

And while experts estimate 350,000 to 500,000 people will travel to Rio for the Olympic and Paralympic Games, that number is only 0.25 percentof total travel to and from countries where Zika is spreading.

Compared with all travel to Zika-endemic areas, the Olympics account for about one-tenth of 1 percent of travel from the U.S. and globally about one-quarter of 1 percent,” CDC director Tom Frieden said today.

For its most recent risk assessment, the CDC also considered which of the 206 participating countries have had Zika transmission, if they have the Aedes aegypti mosquito, and how much travel there’s been between that country and other affected areas.

Even when mapping out the worst-case scenario in which Olympic travelers got Zika in Brazil and were still infectious when they got home, they found that only four countries had heightened risks as a result of the Games: Chad, Djibouti, Eritrea, and Yemen.

Still, the CDC reminded people that pregnant women shouldn’t travel to Brazil, or any country on the travel advisory list, because of the risk of birth defects.

People who do attend the Games should take steps to prevent mosquito bites while they’re in Brazil and for three weeks (!) after they return in order to reduce the risk that a mosquito on their home turf will pick up the virus and start spreading it locally. Pass the bug spray.